#define  _CRT_SECURE_NO_WARNINGS 1

#include <stdio.h>

int Fibo(int n)
{
	if (n <= 2)
	{
		return 1;
	}
	else
	{
		return Fibo(n - 1) + Fibo(n - 2);
	}
}
int main()
{
	int n = 0;
	scanf("%d",&n);

	printf("%d\n",Fibo(n));

	return 0;
}